Pneumatic hammer



Oct. 23, 1928.

O. E. CLARK PNEUMATIC HAMMER gwwntoz Omarlf ('(brl! Filed June 30, 1924 Patented Get. 23, 1928.

UMTED STAT-ES PAT N OKEF'IQE,

OMAR-E. CLARK-,.OF DENVER, COLORADO, ASSIGNOR,=.BY-MESN,E- ASSIGNMENTS, T0 THE GARDNER-DENVER COMBANY, OF QUINCY, ILLINOIS, A CORPORATION OF DELAWARE.

PNEUMATIC, Hartman,

Application filed June 30, 192} Serial No. 723,363

The present invention relates to that type of motive fluid operated tool in which the supply ot'air or other expansive motive fluid is controlled bythe piston. f

The object is to, provide means whereby the stroke of the piston is materially extended.

Thepresent embodiment is of the type disclosed in Patents Nos, 1,314,288 and 131-1216, both of August26, 1919. v

In theseprior tools it has been found. that the piston does not closely approach theback head inits. rearward stroke, and seemingly the cause ofthis is due to the fact that the .eifective area of the front face of the piston being,considerablyless than that of the rear face and the volume of air admitted to the front end .ofthe pistoncha nber being rela tively. small, and: furthermore as the front live..air port of the hammer remains open only for. a; short portion of, the forward andrear strokes, SL1111C161113;PIGSS111G is not built up in the front. end of the cylin der to carry. the. hainmerby expansionand momen- .-.tumthroughout-the full'rear stroke This probably. is due, to the fact; that, very early in the rear stroke live air is a dmitte dto the,

rear end of the piston chamber, and this acting on practically, the entire diameter of the piston, stops the hammer earlyinthe stroke. To remedy this and permit asubstantially tulL rear, stroke the following.

mechanism has been provided...

In the drawings:

Figure 1 is a longitudinalzsectional view. through avrockfdrill equipped with .the 111- vention,

Figures 2: and 3 are. detail longitudinal 8 views through the valve. chamber, illustrating the valve in its two eXtremeposit-ions, Fgigure lis a crosssect-ional view, taken on the line4tl of Figure .1.

A cylinder member is employed, coni pri s-. ing a barrel .01 body 5, having a piston chamher 6, in which is slidably mounted arecipro;

catory piston 7. The rear end of the. piston chamber is enlarged, as illustratedat 8.; A,

lubricant reservoir 9 is locatedagainst. the

rear end of the barrel, and abutted against j the rear sideofthis lubricator is the integral flange 1.0 of a motive fiuidsupply tube.

11, hereinafter more fullydescribed. This, flange 10 is clamped against the reservoirby a rear head plate 12.

The piston 7 is provided with an internal constant pressure chamber lifi, havinga re} duced bore, 1 1 at its rearpend in which the front end of the supply tube 11 is slidably engaged, said tube constituting means for conveying fluid under pressure tothe chamber 13 and maintaining the supply therein.

Thetube 11 is supplied from any'suitable source, preferablythrough a channel 15 in theback [head;12. i

For the purpose of distribnting thefinid under pressure from the chamber 13' to opposite faces of the piston, forwardly inclined ports 16 open from the front portion. of the chamber l3 tl1rough,the side walls ofthe ber 13 through the, side walls of the. piston,

and these ports areinovab'le into ,and out of communication with. the; enlargement, 8 of the piston chamber [6,, *Front. and rear eX- haust ports indicated at19,and;20 and overrun by the. piston serve, to alternately afford communication between the front and rear pp t en l fi e sto chamber ed m phere.

If fluidunder pressure. is supplied to the internal (pressure chamber 13,- itjwill be evident that, with the pistonin the position shown. in Figure 1,- this fluid will esoape through the portslti and pocket 17 into the;

front; end ofthe, piston chamber, while the rear portQO will be ,uncovered, allowing the exhaust 1110111 13116 rear end ofzsaid piston clianiber. Consequently thepiston will be driven rearwardly until the ports 18 are uncovered, whereupon the exhaust port 940 will;be vclose d, the outletport 16 will also be, closed, and the exhaust; port 19 will-be uncovered to allow the exhaust; of; motive fluid that isin front, of thepiston. The, supply ofunotive fluid through; the ports 18 will operate, againstlthe reanend of-the piston and-drive it; forwardly,

The, front face 21 ofthe piston. is, ofn uch beiobvious that. as soonas theports 16- are clesedxduring the reaWard movement oftthe piston, which.closin Willtake-place shortly after. the pistonlbegins such: rearward move less area thanthe rear, face 22, and-'it ;will;, I

lnent, then the remainder of the rearward movement must be under the expanslon of the air in the front end of the piston cham-' her. As soon as the ports 18 uncover, however, a volume of live air is immediately clenism is employed. Formed on one side of the barrel is a valve casing 23 having a longitudinal. valve chamber 24. An annular groove 25, formed in the peripheral wall of the chamber 24, has communication by means of an outlet port 26 with one of the pockets 17 or in other words, with the front end of the piston chamber. In'rear of the groove '25 is another groove 27, into whichopens an inlet port 28 leading from an intermediate portion of the piston chamber 6 and so arranged that it will be traversed by one of the outlet ports 16 in the piston 7. It may be explained at this point. that the piston 7, as clearly shown in Figure 4, is held against rotary movement by suitable keys 7 engaged in keyways 7 formed in opposite sides of the piston. The front end of the valve chamber 24 has an annular groove 29, from which opens an exhaust port 30. Finally a passageway 31 leads from the enlargement 8 of the piston chamber 6 to the rear end of the valve chamber 24.

' In the valve chamber 24 is located a spool valve 32 having a central peripheral groove The valve is adapted to reciprocate and the limit of its forward movement is de termined by a plug 34, constituting a closure for the front end of the valve chamber. A supply port 35 opens from the front end of V the piston chamber into the front end of the valve chamber at one side of the plug 34 and in advance of the spool valve 32.

The operation of this mechanism is as follows: Assuming the piston in the position shown in Figure 1, its rearward movement "will take place. as above described, and the 7 ports 16 will. be cut off primarily by passing from communication with the pockets 17.

hen the piston is in this position the valve 32 will he in its rearward position, as shown in Figure 1, due to the fact that live air from the front. end of the piston chamber will pass through the port 85 to the front end of the valve chamber and shift the valve rearjwardly, the rear end of the valve chamber,

being open through the passageway31 to the rear end of the piston chamber, and thence to atmosphere throughthe exhaust port 20.

During the rearward movement of the pis ton, the upper port 16 will however traverse the port 28, and consequentlylive air can nesa449 flow through said port 28 through grooves 27, 33 and 25, and thence through the outlet port 26 into the front of the piston chamber, supplying additionahlive air and thus'insuring a more complete rearward movement of the piston. This operation is indicated in Figure 3. hen the port 16 has passed the port 28, the exhaust port 19 will be uncoveredto the front end of the piston, while the supply ports 18 will open into the en: largem'ent 8. 'lVhen this takes place, the piston starts on its forward movement, and at the same time motive fluid delivered into the enlargement 8, will find its way through the passageway 31 and operate against the rear end of the valve 82, while pressure" against the front end of said valve'is re duced because the port 35 is now open through the front end of the piston chamber to the exhaust port 19. The valvewill thereupon shift to the position shown in Figure 2. Consequently grooves'25 and 27 willbe cut from communication with each other and ports 26 and 28 will be c'orrespondingly'cut off. The port 28 being thus closed, the port 16 will pass it without releasing any'air from the chamber 13, but the port 26 will now be in communication with the exhaust port 30, as a consequence of which the closing of the exhaust port 19 by the advancing piston will still leave a su plemental exhaust through the port 30, a lowing the piston to move forward without material resistance so that it will deliver a more powerful blow.

From the foregoing, it is thought that the construction, operation and many advantages of the herein described invention will be apparent to thoseskilled in the art, without further description, and it will be 'unhe r thatialternately deliver fluid to the piston chamber on opposite sides of the piston and said ports being controlled by portions of the cylinder member, a supplemental passageway for motive fluid in the cylinder member having a port traversed by an outlet port of the piston, said supplemental pas sageway having an outlet port opening into the piston chamber on one side of the piston, and an exhaust port, and an automatic valve alternately opening an outlet port and exhaust port. Q

2. In a motor of the characterdescribed,

i the combination with a cylinder member having a piston chamber and a piston therein having an internalmotive fluid supply chamber, of means for maintaining fluid under pressure in said chamber, said piston having spaced outlet ports from the chamber that alternately deliver fluid to the piston chamber on opposite sides of the piston and said ports being controlled by portions of the cylinder member, a valve chamber having an inlet port opening into the piston chamber and traversed by an outlet port of the piston, an outlet port opening into the piston chamber in front of the piston and an exhaust port, an automatic valve in the valve chamber movable to a position to afford communication between the inlet and outlet ports of the valve chamber and to another position to cut off such communication and afford communication between the outlet port and the exhaust port, and a passageway leading from the rear end of the piston chamber to the valve chamber to supply motive fluid to the latter for shifting the valve.

3. In a motor of the character described, the combination with a a cylinder member having a piston-chamber provided with ter-' ternal chamber. and a supplemental passagcway in the cylinder member opening into one of the pockets and having an inlet end traversed by. the outlet port of the piston that moves into communication with said pocket, a main exhaust port from the cylinder covered and uncovered by the piston, a

supplemental exhaust port opening from the same end of the piston chamber as that having the pocket to which the supplemental passageway leads, and an automatic valve,

controlling the supplemental passageway and supplemental eX aust.

In testimony whereof, I aflix my signature.

OMAR E. CLARK. 

